Larvicidal activity of Bacillus Thuringiensis Kurstaki against Tuta Absoluta (Lepidoptera: Gelechiidae)

Abstract

A commercial formulation of Bacillus thurengiensis var Kurstaki (BTK) (IAB Bt) has been shown to be effective in controlling Tutaabsoluta Zeller larvae under laboratory conditions. Five concentrations are tested ((200, .350;500;650et800ppm)by ingestion, on the various larval stages (L1, L2, L3, L4 and L5). The larval mortality caused by BTK swelledwith increasing concentrations. The high concentrations of 650 and 800 ppm give 100% mortality rates for the early stages L1, L2, L3 and L4. Theacute toxicity (LC50) of BTK calculated for all larvae is 517 ppm. The lethal efficacy of BTK is noted 02 days, after the ingestion treatment, for the young stages (L1 and L2) and 04 at 6 days for the older larvae (L3 and L4) with a LT50, all larval stages combined equal to 2.6 days.